Power steering apparatus
a technology of power steering and power steering device, which is applied in the direction of motor/generator/converter stopper, dynamo-electric converter control, instruments, etc., can solve the problem that the power steering apparatus may not control the assist steering effor
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first embodiment
[0079] the power steering apparatus monitors the temperature of control unit 4 and electric motor 31, in order to prevent control unit 4 and electric motor 31 from overheating. The temperature of control unit 4 is directly monitored by temperature sensor 40. On the other hand, the temperature of electric motor 31 is monitored as follows. Motor temperature estimating part 42c estimates or computes an amount of generated heat on the basis of a value of the current supplied to electric motor 31, and estimates an amount of change of temperature of electric motor 31 on the basis of the computed amount of generated heat, and adds the estimated amount of change of temperature to a reference temperature value T0 to produce estimated motor temperature Tmest.
[0080]As described above, according to the related art, when a temperature sensor is judged as failed, then a motor current is limited to a motor current value with which both of a control unit and an electric motor can continuously opera...
third embodiment
[0148]The following describes an example of how the power steering apparatus operates with reference to FIGS. 18A and 18B. FIG. 18A shows how estimated motor temperature Tmest changes with time, while FIG. 18B shows how command assist steering torque ATcom changes with time.
[0149]In the following, estimated motor temperature Tmest when temperature sensor 40 becomes abnormal is assumed to be equal to a temperature value T11. Temperature value T11 is below the lowest assist-limiting temperature Ta of the function of computing second torque limit LIM2 for condition that temperature sensor 40 is normal, and is above the lowest assist-limiting temperature Tb of the function of computing second torque limit LIM2 for condition that temperature sensor 40 is abnormal, as shown in FIG. 17.
[0150]As shown in FIG. 18B, until time t11 after time t0, command assist steering torque ATcom is set to be equal to desired assist steering torque ATdes, because desired assist steering torque ATdes is sma...
fourth embodiment
[0164]The following describes an example of how the power steering apparatus operates with reference to FIGS. 21A and 21B. FIG. 21A shows how estimated motor temperature Tmest changes with time, while FIG. 22B shows how command assist steering torque ATcom changes with time.
[0165]In the following, estimated motor temperature Tmest when temperature sensor 40 becomes abnormal is assumed to be equal to a temperature value T21. Temperature value T21 is below the lowest assist-limiting temperature Ta of the function of computing second torque limit LIM2, as shown in FIG. 20.
[0166]As shown in FIG. 21B, until time t21 after time t0, command assist steering torque ATcom is set to be equal to desired assist steering torque ATdes, because desired assist steering torque ATdes is smaller than temperature-based torque limit ATlim. Accordingly, as shown in FIG. 21A, until time t21 after time t0, estimated motor temperature Tmest increases with increase in desired assist steering torque ATdes.
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